Mars Spaceflight Lens 2/200 mm with Optical Light Amplifier

USSR. Lightweight mirror lens no. 3678, weighing 2.88 kg, designed for spaceflight conditions of the 1980s, without any engraving. Image circle diameter approx. 26 mm, distance from sensor to last glass surface approx. 4 mm. High sharpness in the point image, free of chromatic aberration, even at close range. Diameter of the front lens only: 142 mm, containing a 47.5 mm cover with an internal auxiliary lens of 12.5 mm diameter. This auxiliary lens does not have a focal length; it serves to increase light sensitivity. Length with mounting back: 25 cm. A loose additional mirror lens of approx. 1.4/5 cm fits rotationally symmetrically into this quarter-shell mount. This lens alone (front lens only: approx. 65 mm, cover approx. 30 mm) has an image circle of approx. 15 mm, its distance to infinity is approx. 1–2 mm, point image sharpness is good and without chromatic aberration. It is assumed that this was a system lens – the 2/200 mm alone for photographing a very dark object, where the surrounding starlight could brighten the shadows as background noise thanks to the auxiliary lens (for example, the albedo of Phobos is only 4%, and presumably a front aperture was intended for dimming this auxiliary lens; a thread for this is present). The additional interchangeable mirror lens would have served for spectral imaging with its own sensor. The main lens is in very good condition (2-/2-), the auxiliary lens shows signs of use (3/3). Both lenses (strictly speaking three) clean under point light. Unknown lens of the Soviet Union, probably a prototype.

布雷克拍品等级是为了方便竞买人判断拍卖品的成色而设置的。布雷克等级用1到6级来标注外观和功能的成色，(从非常好到非常差)。 在目录图册里用括号里的2个数字来表示，前一个数字表示外观成色的级别，后一个数字表示功能成色的级别。如(3/2)表示外观成色是3(满意的)，功能成色2(好)。 成色 定义参照下列标准： 1 - 非常好 (未使用过，没有使用痕迹) 2 - 好 (新，极少的使用痕迹) 3 - 满意的 (普通的使用痕迹) 4 - 及格的 (明显的使用痕迹，某个非主要部件是后配的) 5 - 有缺陷的 (极明显的使用痕迹, 某个主要部件是后配的，功能上有缺陷，需要修理) 6 - 非常差 (严重破损, 缺少重要部件)